Centrifugal compressor



Feb. 21, 1967 w, s, CASTLE 3,305,166

CENTRIFUGAL COMPRES SOR Filed Feb. 18, 1965 2 gheets-Sheet 1 58 /Z W W 0L n A! W M a l if u I f6 2; {/5 5 57 z *wl a L 2'8 2:?

{'9 INVENTOR.

(fly/aim: 5. (as/7e ATTORNEY Feb. 21, 1967 w, s. CASTLE CENTRIFUGALCOMPRESSOR Filed Feb. 18, 1965 2 Sheets-Sheet 2 m m w m United StatesPatent Ofiice 3,305,166 CENTRIFUGAL COMPRESSGR William S. Castle,Speedway, Ind., assignor to General Motors Corporation, Detroit, Mich.,a corporation of Delaware Filed Feb. 18, 1965, Ser. No. 433,670 4Claims. (Cl. 230-127) This invention relates generally to a centrifugalcompressor and more particularly to a centrifugal compressor having arotor comprising an impeller with individually mounted vanes and aseparate inducer.

It has been a standard practice for some time to design a compositecentrifugal compressor having the inducer and impeller separate. It islikewise well-known in the art to design a bladed rotor having aseparate hub or disc with axial grooves and a plurality of vanesseparably secured in the grooves. This type of bladed rotor, even thoughappreciably less expensive than a rotor machined from a solid block or acast rotor, however, has not enjoyed widespread use in a centrifugalcompressor because of the need for a curved radial wall between adjacentradial compressor blades to direct the incoming air radially outwardlyas it flows through the compressor. A possible solution to the problemof providing these curved radial walls is to design the hub so that itscircumferential surface forms the radial contour. This solution isobjectionable because too much weight is added to the hub. Anotherpossible solution is to 1 provide some sort of shroud or annulus toestablish the radial wall. The second solution is objectionable becauseassembly of the shroud to the blades and hub would require a segmentedtype shroud which becomes unduly cumbersome and complicated.

It is therefore, an object of this invention to provide a centrifugalcompressor having a rotor which is light in weight and relativelyinexpensive to manufacture.

Another object is to provide a centrifugal compressor rotor havingseparate inducer and impeller portions and in which the impeller portionhas its vanes separably secured to a hub.

Another object is to provide a centrifugal compressor rotor in which thecontour of the wall directing air flow through the compressor isestablished simply and without adding undue weight to the structure.

Another object is to provide a centrifugal compressor rotor having animpeller with separate lblades attached to a hub and in which the wallsbetween the blades which direct air radially outwardly are provided in aunique manner and without adding undue weight to the structure.

Other objects and advantages of the invention will hereafter become morefully apparent from the following description of the annexed drawingswhich illustrate a preferred embodiment and wherein:

FIGURE 1 is an axial sectional view of a portion of a gas turbine engineincluding a centrifugal compressor in accordance with the invention.

FIGURE 2 is a section taken substantially along the line 22 of FIGURE 1and looking in the direction of the arrows.

FIGURE 3 is a perspective view of the compressor rotor made inaccordance with the invention shown in FIGURE 1. It has been partiallybroken away for clarity.

FIGURE 4 is a perspective view of a single impeller blade shown inFIGURE 3.

Referring now to FIGURE 1, a portion of a gas turbine engine is shownwhich includes an annular inlet 12 and an annular wall 14. The inlet 12and the wall 14 house a compressor rotor shown generally at 13. Theannular wall 14 is mounted on a tubular housing 16 which has an internalshoulder 17 to support a collar 18. A Z-shaped 3385,15 Patented Feb. 21,1967 ring 20 has its greater diameter mounted within the tubular housing16 above the collar 18. A split ring retainer 22 holds collar 18 andring 20 against shoulder 17. The collar 18 has an integral portion 19 ofreduced diameter which provides a bearing support for the compressorrotor 13. The compressor rotor which is shown more clearly in FIGURE 3comprises a separate impeller and inducer, 23 and 36 respectively. Theimpeller 23 has a hub 24 provided with a plurality of axial dovetailslots 26 equally spaced about its circumference. A plurality of blades28 have their stalks 30 shaped to fit within the axial slots 26. Eachblade has webs 32 projecting circumferentially from each side of theblade. The webs 32 are arcuate in cross section and extend from theleading edge of the blade 28 adjacent the hub 24 to the trailing edge ofthe blade 28 at its tip. When all of the blades are assembled in the hub24, each web 32 abuts a second web projecting from an adjacent blade.The abutting webs thus form a wall extending between two adjacentblades. No connection is provided between the abutting edges of thewebs, in order to allow radial growth of the blades 28 without loadtransfer through the Webs 32. An annular backplate 34, however, iswelded to the trailing edge of the hub 24 and the trailing edges of thevanes 28 to reduce air leakage past the unconnected edges of abuttingwebs 32. A sealing ring 35 with an annular flange which is fixed toplate 34 has its outer surface grooved to form a labyrinth seal with theZ-shaped ring 20. The lower end of the hub 24 also carries an L-shapedcollar 42 radially inwardly of the ring 35. An inducer 36 comprising adisc 38 with a plurality of radially extending integral vanes 40 isdisposed above the impeller 23 and coaxially therewith. The inducer 36is shown indexed with respect to the impeller 23; however, it may bealigned. The L-shaped collar 42, the hub 24, and the disc 38 areconnected for simultaneous rotation by a pair of drive pins 44 spacedapart.

The combination of inducer and impeller thus assembled is connected tothe turbine shaft 46 by a hollow tiebolt 48. The tiebolt 48 has an upperannular flange 50* with an outer serrated circumferential edge 52. Thedisc 38 carries a pair of lock pins 54 which engages the serrated edge52 on the tiebolt flange 50. These lock pins 54 are spaced 180 apart andare biased upwardly by springs 56. The tiebolt 48 has external threadson its lower end which engage internal threads on the upper portion ofthe shaft 46 concentrically disposed within tubular housing 16. Theupper circumferential edge of shaft 46 is serrated and mates withserrations 47 on the lower circumferential edge of the L-shaped collar42. Torque is transmitted from shaft 46 to impeller 23 and inducer 13through collar 42 and drive pins '44. The axial portion of the L-shapedcollar 42 forms the inner race of a ball bearing 57 whose outer raceabuts the reduced portion 19 of collar 18 which is supported by tubularhousing 16. The compressor rotor thus connected is disposed between theannular inlet 12 and the wall 14 and is journaled in the wall 14. Abovethe compressor rotor is a projectile shaped housing 58 which issuspended concentrically within the axial inlet 12 by struts 60. Variousaccessories 61 for the gas turbine are supported within housing 5 8 andare operatively connected to the shaft 46 by an accessory drive shaft 62which is splined to an internal tubular portion 64 on tiebolt 48. As canbe seen in FIGURE 1, air flow through the compressor will be through anannular channel formed by an outer wall comprising the annular inlet 12and by an inner wall comprising the outer surface of projectile housing58 which is contiguous with the outer circumferential surface of thedisc 38, which in turn is contiguous with the u) walls formed by thecircumferentially extending webs 32 on the vanes 28.

Thus it can be seen that I have invented a centrifugal compressor whichincludes an impeller having separably mounted blades with air directingwalls provided therebetween in a unique manner and without adding undueweight to the assembly.

It should be understood, of course, that the foregoing disclosurerelates to only a prefered embodiment of the invention and that it isintended to cover all changes and modifications of the example of theinvention herein disclosed which are within the spirit and scope of theinvention.

I claim:

1. A centrifugal compressor comprising an annular shroud,

an impeller rotatably mounted in said shroud, said impeller comprising ahub,

a plurality of circumferentially spaced blades individually mounted onsaid hub and extending radially therefrom,

a pair of radially arcuate webs extending circumferentially in oppositedirections from each blade and extending radially from the leading edgeof said blade adjacent said hub to the trailing edge of said bladeadjacent its tip, said webs abutting webs extending from adjacent bladesto form walls between said blade and said adjacent blades,

an inducer rotatably mounted in said shroud coaxially with saidimpeller,

said inducer comprising a disc with radially extending blades,

means to drivingly connect said inducer to said impeller,

and

an annular flow channel through said compressor, said flow channel beingbounded by an outer wall comprising said shroud and an inner wallcomprising the outer surfaces of said disc and said Walls.

2. A centrifugal compressor comprising an annular shroud,

an impeller rotatably mounted in said shroud, said impeller comprising ahub,

a plurality of circumferentially spaced blades individually mounted onsaid hub and extending radially therefrom,

a pair of radially arcuate webs extending circumferentially in oppositedirections from each blade, said webs abutting webs extending fromadjacent blades to form walls between said blade and said adjacentblades,

an inducer rotatably mounted in said shroud coaxially with saidimpeller, said inducer comprising a disc with radially extending blades,

means to drivingly connect said inducer to said impeller,

and

an annular flow channel through said compressor, said flow channel beingbounded by an outer wall com- 4, prising said shroud and an inner wallcomprising a portion of said disc and said walls. I

3. A centrifugal compressor comprising an annular shroud,

an impeller rotatably mounted in said shroud, said impeller comprising ahub,

a plurality of circumferentially spaced radial blades individuallymounted on said hub,

at least one web extending circumferentially from each blade to form aradially extending wall between said blade and an adjacent blade,

an inducer rotatably mounted in said shroud coaxially with saidimpeller, said inducer comprising a disc with radially extending blades,

means to drivingly connect said inducer to said impeller, and

an annular flow channel through said compressor, said flow channel beingbounded by an outer wall comprising said shroud and an inner wallcomprising a portion of said disc and said radially extending walls.

4. A centrifugal compressor comprising an annular shroud,

an impeller rotatably mounted in said shroud, said impeller comprising ahub,

a plurality of circumferentially spaced radial blades individuallymounted on said hub,

radially extending walls between adjacent blades of said plurality ofblades, each of said walls comprising at least one web extendingcircumferentially from one of said adjacent blades to the other of saidadjacent blades,

an inducer rotatably mounted in said shroud coaxially with saidimpeller, said inducer comprising a disc with radial blades,

means to drivingly connect said inducer to said impeller for rotationtherewith, and

an annular flow channel through said compressor, said flow channel beingbounded by an outer wall comprising said shroud and an inner wallcomprising a portion of said disc and said radially extending walls.

References Cited by the Examiner UNITED STATES PATENTS 958,129 5/1910Huguenin 230-134 2,216,747 10/1940 Klimek 103-115 2,317,543 4/ 1943Livingston 230-134 2,745,597 5/ 1956 Sinclair et al 230-134 2,889,107 6/1959 Stalker 230-134 FOREIGN PATENTS 614,865 2/ 1961 Canada. 1,337,0947/1963 France.

908,424 10/ 1962 Great Britain.

D-ONLEY I. STOCKING, Primary Examiner. HENRY F. RADUAZO, MARK NEWMAN,Examiners.

1. A CENTRIFUGAL COMPRESSOR COMPRISING AN ANNULAR SHROUD, AN IMPELLERROTATABLY MOUNTED IN SAID SHROUD, SAID IMPELLER COMPRISING A HUB, APLURALITY OF CIRCUMFERENTIALLY SPACED BLADES INDIVIDUALLY MOUNTED ONSAID HUB AND EXTENDING RADIALLY THEREFROM, A PAIR OF RADIALLY ARCUATEWEBS EXTENDING CIRCUMFERENTIALLY IN OPPOSITE DIRECTIONS FROM EACH BLADEAND EXTENDING RADIALLY FROM THE LEADING EDGE OF SAID BLADE ADJACENT SAIDHUB TO THE TRAILING EDGE OF SAID BLADE ADJACENT ITS TIP, SAID WEBSABUTTING WEBS EXTENDING FROM ADJACENT BLADES TO FORM WALLS BETWEEN SAIDBLADE AND SAID ADJACENT BLADES, AN INDUCER ROTATABLY MOUNTED IN SAIDSHROUD COAXIALLY WITH SAID IMPELLER, SAID INDUCER COMPRISING A DISC WITHRADIALLY EXTENDING BLADES,